1. Field of the Invention
This invention relates to a break-away coupling for mounting an elongated member.
2. Description of the Prior Art
Highways and city streets, parking lots, and the like usually have many sign posts located along their boundaries or marking special areas. Frequently these sign posts are hit by vehicles and the post is bent or broken off and must be replaced. Hitting a rigid unyielding signpost damages both the vehicle and the post, and the broken and/or bent posts pose a hazard to any vehicle or pedestrian passing by. The posts are also expensive to replace. In order to replace most broken or damaged posts, the complete post is replaced, including that post portion which is retained in the concrete of the street or in the ground. It is therefore beneficial to have such sign posts held in position in a manner such that if hit they break apart at a predetermined point (yielding to the impact and lessening the damage to the vehicle). Also, if the predetermined point is above the ground, the below-ground post section will not need to be replaced.
Many have addressed the problem of sign post damage by supplying break-away or fracturable posts, brackets and/or couplings. Most have attempted to solve the problem by supplying sectional posts or support structures. U.S. Pat. No. 1,373,979. Ryal discloses a pole supported on a base plate. A bolt forms a swivel connection between the base and the pole. This use of a center pin to couple abutting structures is common. While Ryal's device allows for swivel movement of the post on the base support, it does not provide for break-away coupling.
U.S. Pat. No. 4,171,919--Wills discloses identical but oppositely oriented complementary connecting portions which mate to form a space through which a deformable coupling member is inserted. When hit, the connection disconnects, but the structural elements remain undamaged.
U.S. Pat. No. 3,628,296--Henry discloses a telescoping assembly in which each section is preforated longitudinally, the sections held to each other by inserting connecting means between aligned perforations. When hit, the post breaks because of its relatively weakened nature caused by the perforations. Obviously, both telescoping sections of the post must be replaced each time the post breaks.
In other disclosures abutting posts are set end-to-end on pins which are placed in a vertical axis of the posts and the pins are made narrower or less able to withstand stress than the posts so that the pins break, causing the post sections to disconnect, but not themselves to break or deform. Such shear pins are provided as single bolts on the central vertical axis or as a plurality of vertically aligned pins. Such connection is found in U.S. Pat. No. 1,610,414--Bernard which employs sectionalized rod with center axial holes to receive a spring-set pin. When hit, the spring releases the pin and the rods separate. U.S. Pat. No. 4,441,288--Fledman discloses a swivel joint for connecting sections of drill pipe. The sections are rigidified to one another by a plurality of frangible pins which break under strain before the strain becomes great enough to break the drill. U.S. Pat. No. 3,355,998--Roemisch discloses abutting pole members with aligned recesses into which a fracturable plug is inserted. When the pole is hit, the fracturable plug breaks, allowing the pole members to disconnect.
U.S. Pat. No. 3,127,870--Beiber discloses a break-away rail for race tracks, wherein a plurality of co-linear sections are attached end-to-end by means of breakable intermediate connectors. The connectors are joined to each pipe section by through-bolts. Each connector has a weakened area aligned to the point of intersection of the pipe sections. When hit, the connector breaks at its weakened area and the pipe sections disconnect.
Another disclosure which employs an external connector rather than an internal vertical pin is U.S. Pat. No. 4,529,161--Lockwood in which a break-away mirror is held to the exterior of a vehicle by bracket which has abutting face-to-face plates. One plate is attached to the vehicle and the other to the mirror. The plates are encased in a resin with a frangible area aligned with the plane of abutment of the plates. When the vehicle mirror hits an impediment, the case breaks apart and the mirror detaches from the vehicle.
To date there is no break-away coupling which employs cup-shaped members overfitting either tubular or shaft-like post and stake members and which is reassembled by replacing the shear bolt only, thus being more economical and more simply repaired than the prior art.